A Few Areas I Am Confused About, Please Comment

I am building a workstation computer to build large 3d models in 3ds, maya and cinema 4d. I have done a lot of research into this but with some information being old I thought it best to ask.

For my purposes of only 3d modelling programs, no gaming, what would my best choice be with a budget of about 1k for Cpu and 500-1500 for video cards.

i7 vs dual xeon?
i7 is newer and faster i understand but sr-2 dual xeon workstations seem popular aswell

GTX580, Quadro 4000, tesla?
I know the GTX580 is the most powerful but the drivers for the quadro are optimized for certain programs, but I also read this was just to speed up render times. I know very little about the tesla.

Thanks in advance!!!

You can't go into this with discrete CPU and GPU budgets. I'd say you're looking at a 3930K or 3960X workstation, Sandy Bridge-E. I don't know much about Xeon, but I don't think it'll be worth the money.

My dudget is about 3500-5000 for everything. I am open to any suggestions! When are the 8core sb xeons coming out/ how much?

Unless Autodesk has changed things dramatically in the last couple years, video cards do not improve render times, the CPU is what does the rendering. A good GPU is important for keeping a good FPS and preventing lag while working within your scene, the more complex the scenes your working on(more advanced lighting, more polys, etc) require more graphics power to render in real time as you do your work. The final render that you output for video/images gets done by the CPU.

I would invest more into the CPU rather than GPU, but I'm not entirely sure what type of work your doing. I don't use 3ds max for anything professional, but I've got a Phenom II X6 and radeon 5670 and haven't had any performance issues, wish I had a stronger CPU though cause it can take for ever to render at times.

Oh and I7 isn't newer or better than Xeon, Xeon is just the name of Intel's server parts, there have been I7s and Xeons built on the same processor architecture and the xeons end up with more cores and better performance for workloads that can use those cores.